Only 11,000-22,000 couples were expected to enter civil partnerships in the first five years. Photograph: Linda Nylind for the Guardian

The popularity of civil partnerships has far outstripped official expectations, with figures showing five times as many couples have made the commitment than originally forecast. The latest figures, published on Tuesday, show the number of couples entering civil partnerships in Britain rose by 6% last year to 6,795.

More than 100,000 people have now entered a civil partnership in Britain since they first became legal in December 2005. The 106,834 people far exceeds initial official estimates that between 11,000 and 22,000 would make the commitment in the first five years.

The latest figures also confirm that in the first years more men than women formed civil partnerships, but since 2009 the numbers have become more equal. The average age for entering a civil partnership is just over 40 for men and 38 for women.

In 2006, the first full year that civil partnerships were legal, more than 16,100 were formed. The numbers dipped to 6,281 in 2009, but rose to 6,795 in 2011. There were slightly more male civil partnerships last year: 3,351 compared with 3,444 female .

The figures show 554 civil partnerships were formed last year in Scotland. A total of 89 were formed in Northern Ireland – a drop from the 116 recorded in 2010.

Andy Wasley, from Stonewall, said: "We're delighted that civil partnerships have proved to be so popular, both with same-sex couples and in wider society. YouGov polling for Stonewall shows four in five people across Britain support civil partnerships, and seven in 10 support equal marriage. This modest step towards full equality needn't take much parliamentary time. It's time for the government to get on with it."

The number of dissolutions of civil partnerships is also rising. In 2011 962 were dissolved, an increase of more than 28% compared with the previous year. Nearly twice as many women dissolved their partnerships – 434 couples, compared with 238 male couples.

The most popular local authority to hold a civil partnership outside London remains Brighton and Hove, which saw 222 ceremonies last year. In London, the most popular boroughs were Westminster with 275, Islington with 145 and Camden with 132. Outside London, there were 139 in Manchester and 74 in Birmingham.

The Civil Partnership Act 2004 allowed same-sex couples in the UK to register their relationships for the first time. People who enter civil partnerships get a package of rights and responsibilities, including on tax and benefits, and the ability to apply for parental responsibility for their partner's children and for the full range of financial orders available to married couples on divorce.

A ban on allowing religious buildings to be used to host civil ceremonies in England and Wales was lifted last year by the home secretary, Theresa May. The government has announced that it intends to legislate to give full marriage rights to lesbian, gay, bisexual and transgender people by the next election. Ministers have made clear that the change will not apply to religious marriages in England and Wales.

But there were warnings yesterday that David Cameron risks upsetting grassroots Conservative activists – whose help he will need at the next general election – if he presses ahead with plans to legalise gay marriage. Emma Pidding, the chairman of the party's National Convention told the BBC the issue was of interest to just "a few individuals". She added: "My concern is that we are potentially upsetting our members and activists when I have one goal, and that is to obtain a Conservative majority government in 2015. Anything which upsets any of my members, I don't like to see that."

The Scottish government announced on 25 July it would bring forward moves to make same-sex marriages legal in Scotland, including those conducted by religious bodies.

A Home Office spokesperson welcomed the figures and said those already in a civil partnership would be able to convert their union into a marriage under proposals already published: "This government believes society is stronger when couples commit to each other, which is why it is so encouraging to see more same-sex couples entering civil partnerships.

"We now want to make it possible for all couples, regardless of their gender, to get married. We will announce the results of our consultation by the end of the year."

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